One of the pivotal contrasts in philosophy, which from its earliest times has contrasted the world of ‘mere’ appearance—often argued to be contradictory, confused, a mere shadow of something greater—with what is real, and therefore (perhaps) of more value, timeless, eternal, and when it can be apprehended as it is, a fount of understanding and wisdom. The contrast is central to many Eastern philosophies, to Plato, and in religious form in Christianity. It is also prominent in Kant, where the phenomenal world is conditioned by the mind’s perceptual powers, in contrast to the noumenal world which is not, but which therefore remains unknowable. In reaction many modern philosophies have tried to overcome the dichotomy. It gains its purchase mainly from the phenomena of illusions, where the way we take things to be indeed contrasts with how they are (see illusion, arguments from). But, it is argued, illusion is essentially a local matter, only identifiable against a contrasting background of veridical perception. Equally, to know or to describe how things appear is essentially parasitic on being able to know or describe how things are. Such arguments have an ancestor in Aristotle, who considered that our words gain their sense only by contact with what is real. In modern writings they are found in Wilfrid Sellars, J. L. Austin, and Wittgenstein, while an earlier and amusing anticipation is chapter 4 of The Twilight of the Idols by Friedrich Nietzsche.